Sustaining the reach of a scalable weight loss intervention through financial incentives - a pragmatic, online randomized trial protocol.

Abstract Background High attrition following initial enrollment in evidence-based weight loss programs is a common, challenging, and under-studied issue. A behavioral economics approach consisting of modest monetary incentives may help to engage participants beyond enrollment to close the initial attrition gap. Purpose To describe the methods and design of a pragmatic, online randomized controlled trial (RCT) of an incentivized, technology-facilitated weight loss program through an innovative research-practice partnership involving primary care, health promotion researchers, and a small business. Methods This study is a four-arm (1:1:1:1) RCT that compares the efficacy of outcome-based (weight loss), process-based (weighing in), a combination of outcome- and process-based, or choice-based incentives on sustaining program reach after initial enrollment for an evidence-based weight loss program. The study will enroll 400 individuals aged 19 and older who have a body mass index ≥25 kg/m2, and have reliable access to the Internet or a smart phone. Participants will be followed for 3, 6, 9, and 12 months to assess program reach and representativeness, and continued participation after enrollment. The secondary outcomes include weight loss and program implementation costs. We will conduct participant focus groups to understand the barriers and facilitators of participation and key informant interviews focusing on clinic managers and care providers to explore the potential for future adoption and implementation of the evidence-based program. Discussion This study possesses the potential to close the attrition gap after initial enrollment in a web-based digital weight loss intervention in the primary care and community settings. Clinicaltrials.gov registration NCT04225234.